This invention relates to packing or seals and more particularly to a composite packing or seal fabricated from a particular blend of fibers including polyphenylene sulfide fibers.
Methods for preparing polyphenylene sulfide fibers are described in U.S. Pat. Nos. 3,898,204 and 3,912,695. Such fibers have several desirable properties including high strength, high melting point and non-burning characteristics. The fibers are also relatively unreactive with many corrosive materials including commonly used acids and bases.
Materials containing polyphenylene sulfide have heretofore been proposed as a packing or gasket material. U.S. Pat. No. 4,056,594 describes the extrusion of a solid rod containing solid polyphenylene sulfide and polytetrafluoroethylene, together with optional fillers, such as glass, asbestos, carbon, and the like. Similarly, U.S. Pat. No. 4,050,701 discloses the formation of a seal containing a mixture of polyphenylene sulfide and polytetrafluoroethylene. These materials, however, are relatively expensive to produce and require the use of relatively high proportions of costly materials.